Two weeks ago, ProClub (a.k.a Microsoft gym) introduced a new lock system in the locker room, which requires inserting your member card before locking the cabinet. I left my member card inside the lock the first time I use it. I am a discipline person, left or forgot something rarely happen to me. I only left my work badge once, even that time I was still carrying the empty badge holder.
I blamed myself for being careless. The next day, I went to ProClub to get my card back. The front desk lady was so nice to me. She went to an A4 printer paper box fully stacked with member cards. She grabbed hand full cards with last name start with “G”. I felt less guilty since my last name is only 2 characters, which could be easier for her to help me find my card back. It is all because of my carelessness. I asked her how many member cards in that box? “Few hundred” she answered peacefully and said “thanks for your patient”. I roughly estimated: an A4 box can hold nearly 4 ~ 5 hundred cards; From another angle, a hand full of cards can be 50 to 70, which all have last name start with “G”! Assuming five thousand people visit ProClub every day, nearly 10% people left their cards in the lock for the single day, and it was already the second week after the new lock system was in place. If 10% people make the same mistake, it could no longer be called “user error”. I felt relieved and I know whom I should blame – the lock designer.
What’s the requirement? What is the problem the designer was trying to resolve? I asked the front desk lady, the old locks system work perfect for me and why we change them. The answer is to prevent single person from using multiple lockers. (I do not want to argue if it is a valid requirement. We assume it is valid.)
What’s the design problem? I’d say the lock does not provide a way to remind the user of leaving member card inside the lock. Or put in another way, the design does not provide necessary indication of the existence of member card in the lock.
How to solve the problem? Simply put, provide necessary feedback. There are two solutions in my mind. #1: make the front panel keep on flashing light as long as there is a card inside the lock. #2: after user unlocks the cabinet, the lock should keep on beeping until the owner removes the card from the lock.
How to prevent this happen to me? I will program my life to prevent this happen to me again. Did I just say “program my life”? Yep, I am damn good software engineer. I will wrap my sock around the visible part of my card after inserting it to the lock. When I dress, it will remind me of removing my member card from the stupid lock.